Incommensurate Counterrotating Magnetic Order Stabilized by Kitaev Interactions in the Layered Honeycomb ${\alpha}$-Li$_2$IrO$_3$
| Autor: | Williams, S. C., Johnson, R. D., Freund, F., Choi, Sungkyun, Jesche, A., Kimchi, I., Manni, S., Bombardi, A., Manuel, P., Gegenwart, P., Coldea, R. |
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| Rok vydání: | 2016 |
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| Zdroj: | Phys. Rev. B 93, 195158 (2016) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.93.195158 |
| Popis: | The layered honeycomb magnet $\alpha$-Li$_2$IrO$_3$ has been theoretically proposed as a candidate to display novel magnetic behaviour associated with Kitaev interactions between spin-orbit entangled $j_{\rm eff}=1/2$ magnetic moments on a honeycomb lattice. Here we report single crystal magnetic resonant x-ray diffraction combined with powder magnetic neutron diffraction to reveal an incommensurate magnetic order in the honeycomb layers with Ir magnetic moments counter-rotating on nearest-neighbour sites. This type of magnetic structure has not been reported experimentally before in honeycomb magnets and cannot be explained by a spin Hamiltonian with dominant isotropic (Heisenberg) couplings. The magnetic structure shares many key features with the magnetic order in the structural polytypes $\beta$ and $\gamma$-Li$_2$IrO$_3$, understood theoretically to be stabilized by dominant Kitaev interactions between Ir moments located on the vertices of three-dimensional hyperhoneycomb and stripyhoneycomb lattices, respectively. Based on this analogy and a theoretical soft-spin analysis of magnetic ground states for candidate spin Hamiltonians, we propose that Kitaev interactions also dominate in $\alpha$-Li$_2$IrO$_3$, indicative of universal Kitaev physics across all three members of the harmonic honeycomb family of Li$_2$IrO$_3$ polytypes. Comment: 13 pages, 8 figures |
| Databáze: | arXiv |
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